PaleoBios 29(1):13–23, June 22, 2009 © 2009 University of California Museum of Paleontology A new immigrant mustelid (, Mammalia) from the middle Temblor Formation of central California

zhijie jack tseng1,2, Xiaoming Wang 2, J.D. Stewart2 1Integrative and Evolutionary Biology Program, Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA, USA 90089-0371; [email protected]. 2Department of Vertebrate Paleontology, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA, USA 90007

A new mustelid genus from the Barstovian (middle Miocene) marine Temblor Formation in California is described. The material of Legionarictis fortidens includes an incomplete cranium with partial upper dentition. The straight lingual border and slightly expanded posterointernal cingulum of M1 are plesiomorphic traits, as in the European Dehmictis. However, the M1 is not as posteriorly expanded, and the P4 does not have a lingual hypoconal crest, differentiating L. fortidens from younger North American forms. Furthermore, the P4 protocone is posteriorly placed from the para- style crest, as in the extant South American Eira. An autapomorphic feature of L. fortidens is its highly hypertrophied P4 paracone with a bulbous crown. The robust upper carnassial, very strong development of the sagittal crest, and derived enamel microstructure all suggest a hard food component in its diet. The coastal depositional environment indicated by the presence of marine taxa in the Temblor Formation suggests that hard shelled invertebrates might have been a food source of L. fortidens. A combination of plesiomorphic and derived dental characteristics puts the new form at an evolutionary stage basal to otters and closer to the living Eira. Cladistic analysis of craniodental characters suggests that L. fortidens is more derived than generalized basal mustelines of the Old World, and may have diverged from the lutrine lineage in a separate immigration event to the New World.

INTRODUCTION California Museum of Paleontology in Berkeley, California. Paleontological exploration in 1913 by the University of Comparative materials are housed at the Natural History California Museum of Paleontology to the western edge Museum of Los Angeles County, California and the American of the San Joaquin Valley in central California uncovered Museum of Natural History, New York. Cladistic analysis was fossiliferous marine sandstone deposits of middle Miocene conducted using PAUP* (Swofford 1993) with the heuristic age (Merriam 1914) (Fig. 1). The local fauna, subsequently search algorithm. All measurements were taken with a Mitutoyo named the “Merychippus zone”, contains both terrestrial and marine taxa (Merriam 1915). Collections by other institutions since then have produced additional large and small (Bode 1935). In 2004, one of us (JDS) oversaw a paleon- tological mitigation project for the construction of a power transmission line near Monocline Ridge north of Coalinga, and uncovered a new bone bed in the Temblor Formation (Kelly and Stewart in press) (Table 1). Among the more than 1,200 vertebrate fossils collected from the new bone bed is a partial cranium of a new, unusual form: a large mustelid with very robust carnassial morphology and enamel micro- structural modification towards durophagy. Considering the proximity of the Merychippus zone fauna to the coast during the middle Miocene, this new mustelid might have consumed shelled invertebrates using its robust carnassials. The distinc- tive features of the new form warranted the naming of a new genus and species. Its phylogenetic affinity lies in the middle Miocene diversification of basal mustelines. Furthermore, its basal position to the otters suggests that this new form probably split off from the lutrine lineage sometime in the early to middle Miocene, representing a distinct immigrant lineage from the Old World. Figure 1. Map showing location of the Monocline Ridge as- MATERIALS AND METHODS semblage locality (UCMP V99563). Topographic map modified The new material studied is housed in the University of from 1:24000 scale U.S. Geological Survey map. 14 PALEOBIOS, VOL. 29, NUMBER 1, JUNE 2009 vernier caliper to the nearest 0.1 mm. Reconstructed illustration of the cranium was done using a traced outline of a photograph Table 1. A preliminary faunal list of the Monocline Ridge as- of the specimen. Examination of enamel microstructure was semblage (UCMP V99563). Modified from Kelly and Stewart done using a dissection light microscope. (in press).

INSTITUTIONAL ABBREVIATIONS Amphibia F:AM: Frick collection, American Museum of Natural Anura, sp. undetermined History, New York, NY, USA Eureptilia BM: British Museum, London, UK ophidia KUVP: University of Kansas Museum of Natural History, Colubridae Lawrence, KS, USA Masticophis or Coluber sp. LACM: Natural History Museum of Los Angeles County, testudines Los Angeles, CA, USA testudinidae LACM[M]: Mammalogy Collection, LACM Hesperotestudo sp. of the H. osborniana-orthopyga NMNH: National Museum of Natural History, Wash- lineage ington, DC, USA Aves UCMP: University of California Museum of Paleontology, anseriformes Berkeley, CA, USA anatidae UMMP: University of Michigan Museum of Paleontology, Branta cf. B. woolfendeni Ann Arbor, MI, USA anatid, sp. undetermined Podicepidae SYSTEMATIC PALEONTOLOGY Passeriformes, sp. undetermined class: mammalia Linnaeus 1758 Mammalia order: carnivora Bowdich 1821 artiodactyla family: Fischer de Waldheim 1817 antilocapridae subfamily: mustelinae Fischer de Waldheim 1817 Cosorycinae, gen. and sp. indeterminate Legionarictis fortidens Camelidae (Table 2, Figures 2–10) Miolabis sp. camelid, sp. undetermined Holotype—UCMP 166190, partial cranium with left I1-2, P2-4, right P2, and fragmentary left and right M1s. Carnivora Type locality—UCMP V99563 “Monocline Ridge as- Felidae semblage,” 30 km north of the North Coalinga quarry near Pseudaelurus marshi Coalinga, California. The locality is on a small hill of the Mustelidae Monocline Ridge between Panoche Creek and Arroyo Cierro Legionarictis fortidens sp. et. gen. nov. (Kelly and Stewart in press). See Table 1 for a preliminary Martes cf. M. glarea faunal list of the locality. amphicyonidae Age and stratigraphy—UCMP V99563 is near the top Amphicyon ingens of the marine sandstone/pebble conglomerate Temblor For- Canidae mation, which is overlain by the non-marine cross-bedded Microtomarctus conferta calcareous sandstone, mudstone, claystone, and pebble Borophaginae, sp. undetermined conglomeratic Oro-Loma Formation (Bartow 1996). Based Lagomorpha on a study of perissodactyl and artiodactyl biochronology Leporidae, sp. undetermined (Kelly and Stewart in press), the locality is of early to early Perissodactyla late Barstovian North American Land Age (middle equidae Miocene) in age. Archaeohippus mourningi Etymology—Legionarius, a legionary soldier of the Ro- Desmatippus avus man Republic Period; ictis, weasel—generic name refers to “Merychippus” californicus the prominent sagittal crest of the holotype, reminiscent of “Merychippus” brevidontus the longitudinal helmet ornamentation of Roman legionaries “Merychippus” cf. “M.” relictus and centurion officers. Fortis, strong; dens, tooth—specific rhinocerotidae name refers to the robust carnassial of the holotype specimen. cf. Peraceras sp. Diagnosis—large mustelid, with very prominent sagittal Proboscidea, sp. undetermined crest similar to older individuals of the Eurasian badger (Meles rodentia, two undetermined. spp. Boddaert 1785); infraorbital foramina small, immediately TSENG ET AL.—NEW MUSTELID FROM THE MIDDLE MIOCENE TEMBLOR FM. OF CA 15 above posterior root of P3 as in most basal mustelines; upper tooth formula 3/1/3/1/; I3 unenlarged, as in basal muste- lines; P2-3 slender and simple, without accessory cusps; P4 protocone posteriorly offset from parastyle crest, slightly an- terior in position to paracone, similar to Martes Frisch 1775; carnassial notch absent as in all neomustelids, P4 paracone very robust, labially and lingually inflated, invading the proto- cone space; P4 hypoconal crest absent as in basal mustelines; M1 triangular in occlusal view, with well-formed, straight lingual cingulum; posterior cingulum slightly expanded, M1 labial roots close together or fused, intermediate between the morphology observed in basal mustelines and lutrines. Description—Cranium: The entire cranium is dorsoven- trally deformed; the compression is more severe on the right half in the ventrolateral direction (Figs. 2–5). Associated with this asymmetrical deformation, much of the right upper dentition and zygomatic arch are destroyed. The nasal open- ing is dorsoventrally compressed to a width of 9.1 mm and a height of 4.0 mm; the nasal bones have been pressed into the nasal cavity, displacing the premaxilla and maxilla later- ally. The entire rostrum is 30 mm long between the anterior tip of the premaxilla and the anterior edge of the orbit. The antorbital fossa extends 11.5 mm anterior of the orbit. The infraorbital foramina are 2.4 mm wide and 3.34 mm high; they are situated ~11 mm dorsal of the posterior base of P3. Postorbital processes are not particularly prominent; two prominent frontal ridges lead from the postorbital processes and converge to form the sagittal crest ~8.4 mm posterior of the orbit. The sagittal crest rises gradually over the posterior cranium, reaching a maximum height of 14.0 mm; the crest measures 61.9 mm from the convergence of the frontal ridges to the posterior end, which terminates into a notch that over- hangs the occiput. The narrowest region of the cranium is a gradual constriction 13.3 mm posterior to the postorbital processes. The zygomatic arch is slender, measuring 6.5 mm in depth. The lateral sides of the frontal and parietal regions are badly damaged; no foramina are visible. The cranial re- gion does not appear particularly inflated or box-like, even after dorsoventral compression is taken into account. On the dorsolateral surface of the posterior cranial region there are vertical linear rugosities. The lambdoidal crests are destroyed, but at the junction between the lambdoidal and sagittal crests there is a short ridge running ventrally and smoothly merging with a vertical occiput. There are three incisive foramina immediately behind the incisors on the palate. The paired palatine canals originate at a position adjacent to the P4 protocone, and extend anteriorly Figures 2–5. Skull of Legionarictis fortidens gen. et. Sp. nov., as far as the position of P2. The overall shape of the palate is a UCMP 166190. 2. Skull in ventral view. 3. Left lateral view. 4. Dorsal view. 5. Right lateral view. tapering triangle, with the distance between labial boundaries of M1 approximately equal to that of the toothrow length between C1-M1. The posterior end of the palate extends lock the mandibular condyles in articulation. The foramen well beyond the position of M1; the pterygoid bones extend ovale is immediately medial to the glenoid fossa. The ventral posteriorly to at least the position of the glenoid fossae. The wall of tympanic bulla has been destroyed; the ventral part post-glenoid processes are prominent; they are broken at the of the petrosal and the dorsal roof of the tympanic chamber ventral tips, so it is impossible to discern whether they would is exposed. The foramen rotundum is missing, the postero- 16 PALEOBIOS, VOL. 29, NUMBER 1, JUNE 2009

Table 2. Upper cheek teeth measurements for Legionarictis fortidens, compared with the first known upper dentitions of Dehmictis vorax, Mionictis sp., Sminthosinis bowleri, Trochictis depereti, and Trigonictis kansasensis. L, length; W, width; WaP4, width of anterior P4 at the position of the paracone and protocone; WpP4, width of posterior P4 at the position between the paracone and metastyle. Unless otherwise noted, measurements were taken using vernier calipers to the nearest 0.02 millimeters.

Dehmictis Legionarictis Sminthosinis Trochictis Trigonictis vorax fortidens Mionictis sp. bowleri depereti kansasensis Dehm, 1950 UCMP 166190 F:AM 63296 UMMP V52868 BM M5313 kUVP 4604 left right left right holotype1 holotype2 holotype3 LP2 5.22 5.54 6.50 6.16 5.38 5.0 5.5 WP2 2.88 3.26 3.40 3.26 2.15 2.7 3.6 LP3 7.30 7.96 7.52 7.48 8.01 6.0 7.0 WP3 4.10 4.74 4.30 4.26 2.63 3.4 4.4 LP4 9.7 11.50 — 12.34 12.30 4.60 9.5 11.9 WaP4 6.9 8.28 — — — 5.35 6.7 7.8 WpP4 5.44 — 5.86 5.88 6.6 LM1 5.8 7.72 7.28 11.96 11.82 4.76 5.5 6.8 WM1 9.8 — — 12.92 ~14.28 7.47 12.1

1Bjork (1970); 2Pilgrim (1932); 3Hibbard (1941) ventral part of the basisphenoid is also partially destroyed. Hunter-Schreger enamel microstructural bands (Stefen No evidence of the mastoid process was present. The right 2001) are visible on the cheek teeth under a dissecting paroccipital process is not enlarged; it is anteroposteriorly microscope at 35 times magnification (Table 3). All of the compressed, and points posteroventrally. premolars and molars show the basal carnivoran condition Dentition: Only left I2-3 are preserved; the I3 is only of undulating Hunter-Schreger bands, except for the car- slightly larger in size than I2, and both are unicuspid. No nassial. In the left P4, the top ~66% of the enamel exhibit canine teeth were preserved, but the canine alveoli posi- acute-undulating bands (Figs. 8–9), which are considered to tion indicates the presence of a small diastema between C1 be more derived than the undulating bands (Stefen 1997). and I3. Post-canine teeth are not crowded; there is a small Comparison—The presence of both plesiomorphic and diastema between each of them. Right P2 and left P2-3 are highly autapomorphic characters in Legionarictis, along with unicuspid, with only a weak posterior cingulum. The P4 is the paucity of diagnostic synapomorphic characters shared the most prominent tooth in the dentition; a low parastyle with a particular group of mustelids, made phylogenetic crest is present at the anterior base of the tooth. The para- placement of this new form difficult. The suite of plesio- cone is bulbous, occupying more than half the total length morphic neomustelid characters includes small infraorbital of P4. There is no carnassial notch; the posterior face of the foramina, unenlarged I3 and P4 with simple protocone. A paracone runs into a lower, small metastyle. A strong conical few synapomorphies, namely enlarged P4 protocone, smaller protocone is present, posteriorly set from anterior edge of M1 metacone relative to paracone, and strongly ridged M1 the parastyle crest. There is no hypoconal crest, but there is lingual cingulum, are shared by Legionarictis, early and middle a weak lingual cingulum running along the lingual base of Miocene basal Old World mustelines, the South American the tooth crown. On the right M1, only the posterolingual Eira Jardine 1842, and what has been referred to as Galictini side is preserved; there is a strong posterior cingulum, sur- by Baskin (1998). Morphological affinity among basal Old rounding a small cusp at the lingual corner of the tooth. Only World mustelines Dehmictis Ginsburg and Morales 1992, the lingual cingulum is preserved in left M1; the cingulum Eirictis Qiu et al. 2004, Iberictis Ginsburg and Morales 1992, runs parallel to the sagittal plane of the cranium, and the Trochictis Meyer 1842, New World forms Sminthosinis Bjork anterior border of the tooth appears more or less perpen- 1970, Trigonictis Hibbard 1941, and extant South American dicular to this cingulum. No postprotocrista could be seen taxa Galictis Bell 1826 and Eira have been suggested (Pilgrim on what remains of the M1. The labial roots of M1 appear 1932, Ray et al. 1981, Ginsburg and Morales 1992, Baskin to be very close together, and it is possible they might be 1998, Ginsburg 1999). In addition, the otter-like forms En- fused; this gives the M1 a triangular outline in occlusal view. hydrictis Stefani 1891, Lutravus Furlong 1932, and Mionictis Cheek tooth measurements and comparison to other taxa Matthew 1924 have been suggested to take their root in the are shown in Table 2. Dehmictis group (Baskin 1998, Ginsburg 1999). In light of TSENG ET AL.—NEW MUSTELID FROM THE MIDDLE MIOCENE TEMBLOR FM. OF CA 17 these suggestions, comparisons were made between Legion- from which more derived mustelines and also lutrines origi- arictis and these taxa. nated. Dehmictis is similar to Legionarictis in having conical The basal taxon Dehmictis vorax of early Miocene time P4 protocone, a very weak P4 lingual cingulum, and a straight from Europe was described by Dehm (1950) and designated M1 lingual cingulum. The position of the P4 protocone is by Ginsburg and Morales (1992) as a possible ancestral form more anteriorly situated in Dehmictis; this is a plesiomorphic feature also seen in Martes. In addition, the M1 metacone of Dehmictis remains more comparable in size to the para- Table 3. Hunter-Schreger enamel banding patterns in the cheek cone as in Martes, and not reduced as in more derived fossil teeth of Legionarictis fortidens. The microstructure was observed taxa. Considering these basal features, Dehmictis vorax was at three regions in each tooth: (1) the top 33% of an unworn used as the fossil outgroup while several species of Martes tooth or the occlusal surface if worn; (2) the middle 33% of the were included as an extant outgroup in the cladistic analysis tooth, and (3) the bottom 33% of the tooth near the base of the conducted in this study. tooth crown. An interesting form similar to South American Eira was recently described from the late (2.58–2.15 Ma) Occlusal Mid-section Crown base Longdan Fauna of Gansu Province, China (Qiu et al. 2004). The mustelid Eirictis robusta has a high rostrum, and nasal Left P2 undulating undulating undulating bones that are slightly convex at the anterodorsal margin. Left P3 undulating undulating undulating The maxillary portion of the zygomatic arch is deep above Left P4 acute acute undulating P4, as in Legionarictis. Whereas the antorbital arch is located Left M1 - undulating undulating dorsal to the space between the P4 roots in Eirictis, it ap- Right P2 undulating undulating undulating pears to be more anteriorly placed in Legionarictis; the arch Right P3 - - undulating is situated over the anterior P4 root. Eirictis has enlarged Right M1 - undulating undulating I3 which is not observed in Legionarictis. As in Eirictis, Le- gionarictis shows clear antorbital fossa, delineating the orbit. The distinctiveness of the P4 protocone, having constricted anterior and posterior boundaries, is a symplesiomorphy between Eirictis and other mustelines (Qiu et al. 2004). The more conical shape of the P4 protocone, and the complete lack of a posterior cingulum or hypoconal ridge, both being plesiomorphic traits, prompted Qiu et al. (2004) to distin- guish Eirictis from Pannonictis Kormos 1931, Enhydrictis, Trigonictis, and Sminthosinis. Slightly more derived than Dehmictis, the early Miocene Iberictis is similar to Legionarictis in the conical P4 protocone, straight M1 lingual cingulum, and the overall triangular shape of M1 associated with metacone reduction. Iberictis differs in

Figures 8–9. Views of the left P4 of Legionarictis fortidens under Figures 6–7. Stereopair photos of the left dentition of Legionar- magnification. 8. Labial view at 6x. 9. Labial view at 25x, note ictis fortidens. presence of acute-undulating Hunter-Schreger bands. 18 PALEOBIOS, VOL. 29, NUMBER 1, JUNE 2009 the presence of a lingual ridge on P4, and anterior P4 protocone and anteroposteriorly compressed M1 with round lingual edge. position. In addition, the transverse width of M1 in Iberictis is Among the otter-like forms, Pilgrim (1932) placed the longer than the length of P4 (Ginsburg and Morales 1992). genus Enhydrictis very close to Trochictis. Clear morphologi- From the early and middle Miocene epochs of Europe, cal differences are observed between the the Enhydrictis and the musteline Trochictis depereti (Pilgrim 1932) resembles Legionarictis. Features like the P4 protocone being anteriorly Legionarictis only in its conical P4 protocone. Its P4 has a situated and cuplike, presence of P4 lingual ridge, rounded lingual ridge as well as an anteriorly placed protocone. The M1 lingual cingulum and overall quadrate shape of that tooth M1 is relatively short and not posteriorly expanded. Trochictis in Enhydrictis all indicate close affinity to the morphology also retains a P1. Compared to T. depereti (BM M5313), the observed in middle Miocene lutrines. anterior and posterior faces of P2 and P3 appear more asym- The early Pliocene Lutravus halli is similar to Legionarictis metrical in Legionarictis. The anterior faces tend to appear in the posteriorly placed P4 protocone and straight lingual convex, whereas the posterior face is concave; this gives an M1 (Furlong 1932). It differs from Legionarictis by its en- appearance of a posteriorly tilting premolar crown when viewed larged I3, cuplike P4 protocone, presence of P4 lingual ridge, laterally. Both Trochictis and Legionarictis have elongate, simple and unreduced M1 metacone. P2, unlike the more oval, nearly circular P2 of Eirictis. The P1-3 Both North American and European specimens have been of Trochictis are very similar to that of Martes, with its P2-3 assigned to the Miocene lutrine Mionictis, but the European being simple, elongate, and P1 small and scoop-like; the loss forms have been renamed Lartetictis and Adroverictis (Gins- of P1 in Legionarictis notwithstanding, P2-3 in this new form burg and Morales 1996). Ginsburg and Morales (1996) are probably morphologically conservative, and thus represent considered these two genera to be melines, convergent with symplesiomorphies of aforementioned comparative taxa. the lutrine Mionictis, and both melines and lutrines sharing Pliocene in age and likely an immigrant from the Old affinities to Trochictis. In addition, Ginsburg and Morales World, Sminthosinis bowleri Bjork 1970 from the Hagerman (1992) reassigned Mionictis artenensis to the genus Trochic- Fauna in Idaho, USA, is similar to Legionarictis in its conical tis, citing the expansion of the M1 talon as a trait shared by P4 protocone (Bjork 1970). The major difference lies in the Trochictis, Lartetictis, and Adroverictis. The M1 of Lartetictis anteriorly placed protocone position and quadrate M1 with dubia has a prominent posterolingual cingulum, to a more round lingual cingulum of Sminthosinis. extreme degree than observed in Legionarictis; both Adrover- Trigonictis kansasensis from the late Pliocene Rexroad ictis ginsburgi and A. schmidtkittleri have anteriorly expanded Fauna of Kansas shares with Legionarictis a conical P4 pro- lingual M1 border, not transversely flat as in Legionarictis. tocone (Hibbard 1941). It is different from Legionarictis in Unfortunately, both European genera represent material too that the P4 protocone is anteriorly placed (not posterior of fragmentary to be included in the cladistic analysis. the parastyle crest), and a P4 lingual ridge is present. The M1 There are no published illustrations or photographs of of Trigonictis is quadrate, with a rounded lingual cingulum, upper dentition of North American Mionictis (Jon Baskin both different from the triangular M1 with straight lingual personal communication). However, two specimens were cingulum in Legionarictis. The P4 of Trigonictis macrodon brought to our attention: F:AM 63298 and 63296, associ- (USNM 23664) is nearly identical in size to that of Legionar- ated partial lower jaws and partial anterior cranium with ictis; however, the anterior face of the P4 paracone is straight full dentition, respectively. The specimens came from the in lateral view in Trigonictis, whereas in Legionarictis it is MacAdams quarry of Clarendon Beds of Texas, and are convex. Although both genera lack a carnassial notch, the referred to Mionictis (Harrison 1981). The lower jaws ap- connection between the paracone and metastyle in Trigonictis pear to represent a relatively large species of Mionictis. The forms a much deeper arch than in Legionarictis, which has anterior cranium represents a taxon similar in size. The wide only a shallow depression between the two cusps (Figs. 6–7). internal M1 cingulum of F:AM 63296 approximately occludes The lingual ridge in T. macrodon is characteristically straight, with the m1 talonid and m2 in F:AM 63298, although dif- forming the long edge of the triangular P4 in occlusal view; ferential tooth wear indicates they are from two individuals. in Legionarictis, the protocone border is well-defined and Comparing Legionarictis with F:AM 63296, the former has without a clear lingual ridge or cingulum. unenlarged I3; P2-3 are similarly small and simple in both The South American Eira barbara is similar to Legionaric- taxa; P4 paracone of F:AM 63296 is not bulbous as in Le- tis in its (1) posteriorly placed, conical P4 protocone, (2) lack gionarictis; a weak but definite P4 hypoconal crest is present of a P4 lingual ridge, (3) slender zygomatic arch, (4) small in F:AM 63296; posterior M1 cingulum is more posteriorly infraorbital foramina, and (5) small and blunt paroccipital extended in F:AM 63296; both exhibit a prominent lingual process. One difference is the enlarged I3 in Eira, which is M1 cingulum that is anteroposteriorly straight; M1 is rela- not observed in Legionarictis. tively larger in F:AM 63296. Also South American in distribution, Galictis vittata is similar to Legionarictis in the slender zygomatic arch, small CLADISTIC ANALYSIS infraorbital foramen size, and short paroccipital process. It dif- A parsimony cladistic analysis was performed using 22 fers from Legionarictis in its enlarged I3, cuplike P4 protocone, craniodental characters on fifteen mustelid taxa, including TSENG ET AL.—NEW MUSTELID FROM THE MIDDLE MIOCENE TEMBLOR FM. OF CA 19 major taxa discussed in the comparison section, with the to resolve the disagreements, but that is beyond the scope addition of Lontra Gray 1843 as a representative of extant of this study. As for the placement of Legionarictis fortidens North American lutrine to better evaluate character polar- into a position in musteline evolution, the cladistic analysis ity in the otter-like fossil taxa (Appendices 1–2). Using the shows that it is outside of the otter clade, and closest to the heuristic search option, 132 equally parsimonious trees were living Eira in morphology. obtained. The 50% majority-rule consensus tree of those 132 Some broad morphological patterns can be observed by trees is shown in Figure 11. Three species of Martes were des- comparing the P4-M1 morphology of the taxa across clades ignated as outgroup taxa. In all 132 most parsimonious trees (Fig. 11). The paraphyletic group including Martes to Gulo the taxon Dehmictis vorax is basal to all other taxa analyzed and the fossil taxa between them are all characterized by except for Martes. In 79% of the trees, a clade composed of relatively more anterior position of the P4 protocone, which Eirictis robusta, Sminthosinis bowleri, Trigonictis kansasensis, is aligned with the P4 parastylar ridge, or at a position be- and Gulo gulo appear between D. vorax and the sister clade tween the parastylar ridge and the paracone. In contrast, the composed of the rest of the taxa, which appears in 97% of the clade including otters and the rest of the taxa tends to show trees. Within this last clade, Eira barbara and Legionarictis a more posterior position of the P4 protocone. There is a fortidens appear more basal to the well-supported sub-clade minor trend in the aforementioned clade to enlarge the M1 which includes the otter-like fossil taxa and Galictis. Lutravus relative to the P4, and develop a postero-lingual cingulum halli and Galictis vittata fall at the base of the highest level extension which increases the surface area of M1. Among clade which includes the extant Lontra canadensis and the the other taxa, Gulo gulo is clearly derived in its reduction fossil genera Mionictis and Enhydrictis. of M1 size relative to P4. The cladistic analysis shows that the otter-like clade is well As Legionarictis is without a closely related taxon in the supported (Fig. 11) and is consistent with a recent molecular Miocene fossil record of North America, we suggest that phylogenetic analysis by Fulton and Strobeck (2006). The this new form represents an immigrant lineage from the Old clade Enhydrictis-Mionictis-Lontra precedes the more basal World. With its position basal to the clade of Old World and Lutravus. The grison Galictis is at the base of the otter clade, New World lutrines (Fig. 11), Legionarictis would have im- and in the case of craniodental morphology this taxon is very migrated to North America separately from the invasion of close to Lutravus. In the same analysis, Fulton and Strobeck Mionictis which occurred during the middle Hemingfordian (2006) also found a musteline clade more basal to that of the (Tedford et al. 1987, Tedford et al. 2004). The timing of the otters and weasel; this clade is composed of Martes, Gulo, Legionarictis immigration event would have been sometime and Eira. The morphology cladogram is in overall agree- after the divergence from basal Old World mustelines during ment with the molecular hypothesis; however, the position the early to early middle Miocene, before the Barstovian. This of Eira is closer to that of the otter clade than to the basal scenario would be clarified with discovery of additional related musteline clade. In addition, the Martes-Gulo-Eira clade is forms in the middle Miocene of North America. paraphyletic in our morphological analysis. The addition of species of weasels Mustela and Eurasian badgers (e.g., Meles, Functional Morphology Mellivora) might provide additional morphological disparity The ancestral P4 protocone morphology in mustelines is

Figure 10. Reconstruction of the cranium of Legionarictis fortidens. Left lateral view shown. Illustration by Z.J. Tseng. 20 PALEOBIOS, VOL. 29, NUMBER 1, JUNE 2009

Figure 11. 50% majority-rule consensus tree from 132 most parsimonious trees in a cladistic analysis of basal Old World mustelines and lutrines and their New World relatives. Branch values indicate percentage of all trees with the presence of the clade. Extinct taxa are indicated by a dagger. The P4-M1 dentition of each species is scaled to the same P4 length to show relative differences in dental morphology and size. For character matrix and its description see Table 4 and Appendix. TSENG ET AL.—NEW MUSTELID FROM THE MIDDLE MIOCENE TEMBLOR FM. OF CA 21

Table 4. Character matrix used in cladistic analysis. For description of characters and their states see Appendix.

taxon 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Dehmictis vorax ? 1 0 0 0 0 0 1 0 0 0 0 ? 0 0 0 ? ? ? ? ? ? Eira barbara 1 1 0 0 0 1 2 1 0 1 0 0 0 0 0 0 0 0 0 1 0 0/1 Eirictis robusta 0 1 0 0 1 1 0 0 0 0 0 0 0 0 0 0 1 0 ? ? 1 ? Enhydrictis galictoides 1 1 1 1 0 1 0 ? 0 0 ? 0 0 ? 1 0 ? ? 0 1 ? 0 Galictis vittata 1 1 1 1 1 1 2 1 0 1 0 0 0 0 0 0 1 0 0 1 0 0 Gulo gulo 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 1 1 1 Legionarictis fortidens 1 ? 0 0 0 ? 0 1 ? 1 ? 0 0 1 ? 1 0 0 0 ? 0 1 Lontra canadensis 0 1 2 1 0 1 1 1 1 0/1 0 0 1 0 1 0 1 1 0 1 0 0 Lutravus halli 0 1 1 1 0 1 0 1 0 1 0 0 1 0 0 0 1 ? ? ? ? ? Martes americana 0 0/1 0 0 0 0 0 1 0/1 0 0 0 0 0 0 0 0 0 0 0 0 0/1 Mionictis sp. 1 1 1 1 0 1 0 0 1 0 1 1 1 0 1 0 0 1 ? ? 1 ? Martes martes 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 Martes pennanti 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 1 0 0 Sminthosinis bowleri 0 1 0 0 0 1 0 ? 0 0 ? 0 ? 0 0 0 ? ? ? ? ? ? Trigonictis kansasensis ? 1 1 0 0 1 0 0 0 0 ? 0 ? 0 0 0 ? ? ? ? ? ? small, conical, and lingual to the P4 parastyle (Fig. 11). At (Figs. 8–9, Table 3). Thus there is additional indication that this position, dental occlusion places the protocone between Legionarictis might have consumed hard food such as shell the main cusp of p4, and the paraconid of m1. Posterior or bone. Furthermore, the coastal depositional environment development, either by expanding a P4 hypoconal shelf, or indicated by the presence of both terrestrial and marine taxa by altering the position of the P4 protocone, would bring in the Merychippus zone fauna (Merriam 1915) suggests the it into contact with the m1 paraconid. This suggests that proximity of the terrestrial mammals of the Temblor Forma- carnassial occlusion in Legionarictis would include not only tion to marine waters. Thus, it is possible that Legionarictis shearing, but also direct overlap of m1 paraconid with lingual might have incorporated marine and/or freshwater shelled P4, as in the crushing occlusion seen in posterior molars. invertebrates in its diet. Recent discoveries of a diverse guild Thus, Legionarictis was probably capable of durophagy, the of lutrines from the Toros-Menalla sites in Chad (Peigné et ingestion of tough food, and may have incorporated bone or al. 2008) suggest that even within the lutrine clade there hard invertebrates as part of its diet. However, the degree of were terrestrial ecomorphologies near aquatic environments this diet specialization is not as pronounced as in fossil and but without extensive adaptations for an aquatic lifestyle. extant lutrines, which developed morphologies ranging from Legionarictis could have played a similar ecological role as cup-like P4 protocone (as in Lutravus), to more extended P4 other Miocene mustelids of near-water environments. hypoconal crest and platform (as in Mionictis), to the quadrate The prominent sagittal crest is additional evidence for P4 seen in many extant lutrines. All of these morphological strong bites and hard diet in Legionarictis. The deep sagittal modifications increased the surface area available for occlu- crest provides a relatively large area for the attachment of the sion, and thus probably improved the performance of those temporalis muscles, which along with the masseter are the teeth as crushing tools. primary jaw-closing muscles (Fig. 10). However, it is also Studies of enamel microstructure across Carnivora have possible that the deep sagittal crest observed in Legionarictis shown adaptive trend towards more crack-resistant structure is a sexually dimorphic trait. The depth of the sagittal crest in taxa that incorporate hard food in their diet (Stefen 1994). is sexually dimorphic in Eurasian badgers, but this slight Examination of Hunter-Schreger enamel banding in mustelid differentiation is obliterated when crest depth is compared teeth have shown that Aelurocyon Peterson 1906, Brachypsalis across a wider sample of mustelid taxa (Lee and Mill 2004). Cope 1890, Eomellivora Zdansky 1924, Gulo Pallas 1780, The great development of the sagittal crest observed in Mionictis, and Plesiogulo Zdansky 1924 all show some de- Legionarictis could thus be a combination of biomechanical gree of specialization (Stefen 2001). Consistent with their function and sexual selection. Interestingly, when the ratios robust cranial morphology, the specialized Hunter-Schreger of sagittal crest height to condylobasal length and width of bands probably imply a hard food component in the diet of postorbital constriction to basioccipital width are compared those taxa. In Legionarictis, most of the cheek teeth exhibit among Legionarictis, Meles (n=44), and Lutra Brunnich 1772 the unspecialized undulating enamel banding pattern, but (n=9) using the data from Lee and Mill (2004), Legionarictis the carnassial has a more derived acute-undulating pattern is more similar to Meles in its relatively taller sagittal crest, but 22 PALEOBIOS, VOL. 29, NUMBER 1, JUNE 2009 closer to Lutra in its relatively narrower postorbital constric- Bode, F.D. 1935. The fauna of Merychippus zone, north Coalinga tion. The intermediate morphology of Legionarictis might district, California. Carnegie Institution of Washington Publica- thus indicate an intermediate diet, as those two morphological tion 453:65–96. indicators have been linked to different predatory strategies Bowdich, T.E. 1821. An analysis of the natural classifications of Mam- between the terrestrial badgers and aquatic otters (Lee and malia, for the use of students and travellers. J. Smith, Paris. 115 pp. Mill 2004). Judging from the unworn premolars, the Legion- Brisson, M.J. 1762. Regnum animale in classes IX. Distributum, arictis specimen is probably a young adult individual, even sive, synopsis methodica. Sistens generalem animalium distribu- though no bone sutures could be observed on the cranial tionem in classes IX, & duarum primarum classium, quadrupe- bones. Given its young age, the prominent sagittal crest is dum scilicet & cetaceorum, particularem divisionem in ordines, even more impressive as the crest may continue to develop sectiones, genera & species. T. Haak, Paris. 294 pp. through adult life similar to the patterns seen in some extant Bryant, H.N., A.P. Russell, and W.D. Fitch. 1993. Phylogenetic mustelids (Marshall 1951, Long 1974, Hancox 1988). relationships within the extant Mustelidae (Carnivora): Appraisal of the cladistic status of the Simpsonian subfamilies. Zoological CONCLUSION Journal of the Linnean Society 108:301–334. A new genus of mustelid carnivoran is described from a Dehm, R. 1950. Die Raubtiere aus dem Mittel-Miocän (Burgida- newly discovered bone bed of the middle Miocene Temblor lium) von Wintershof-West bei Eichstätt in Bayern. Bayerische Formation near Coalinga, California. Legionarictis fortidens Akademie der Wissenschaften Mathematisch-Naturwissen- exhibits several highly autapomorphic characters, including a schaftliche Klasse Abhandlungen N. F. 58:1–141. prominent sagittal crest, and hypertrophied P4. Our cladistic Fischer de Waldheim, G. 1817. Adversaria zoologica. Mémoires analysis places this new taxon among mustelines but basal to de la Société Imperiale des Naturalistes de Moscou 5:357–472. lutrines, indicating L. fortidens had only begun to evolve away Fulton, T.L., and C. Strobeck. 2006. Molecular phylogeny of the from musteline ancestral morphology. Its basal position rela- Arctoidea (Carnivora): Effect of missing data on supertree and tive to lutrines indicates that it might have been an immigrant supermatrix analyses of multiple gene data sets. Molecular Phy- from the Old World during a separate immigration event logenetics and Evolution 41:165–181. from the first occurrence of New World lutrines. Its robust Furlong, E.L. 1932. A new genus of otter from the Pliocene of the upper carnassial morphology, derived enamel microstructure, northern Great Basin province. Carnegie Institution of Wash- and cranial shape all suggest a durophagous component in its ington Publication 418:93–103. diet. With a suite of morphological characters intermediate Ginsburg, L. 1999. Order Carnivora. Pp. 109–148 in G. E. Rössner between badgers and otters, Legionarictis might have hunted and K. Heissig (eds.). The Miocene Land Mammals of Europe. both terrestrial vertebrates and aquatic invertebrate prey. Verlag Dr. Friedrich Pfeil, München. Ginsburg, L., and J. Morales. 1992. Contribution à la connaissance ACKNOWLEDGMENTS des Mustélidés (Carnivora, Mammalia) du Miocène d’Europe We thank Pat Holroyd for providing access to the UCMP Trochictis et Ischyrictis, genres affines et genres nouveaux.Comptes holotype specimen for study; Bob Purdy and Dave Bohaska Rendus de l’Académie des Sciences 315:111–116. for their hospitality and assistance with the collection of the Ginsburg, L., and J. Morales. 1996. Lartetictis et Adroverictis, NMNH; Jon Baskin for help on North American Mionictis nouveaux genres de Melinae (Mustelidae, Carnivora, Mammalia) specimens and improving the manuscript; Clara Stefen for du Miocène de l’Ancien Monde. Bulletin du Muséum National constructive comments on the manuscript and illustrations; D’Histoire Naturelle 18:663–671. Ken Finger and Mark Goodwin for editorial assistance; Ted Hancox, M. 1988. A review of age determination criteria in the Connors (LACM) for his partial preparation of the specimen. Eurasian badger. Lynx 24:77–86. This research was funded by a National Science Foundation Harrison, J.A. 1981. A review of the extinct , Plesiogulo Graduate Research Fellowship (to ZJT). (Carnivora: Mustelidae), from North America. Smithsonian Contributions to Paleobiology 46:1–27. LITERATURE CITED Hibbard, C.W. 1941. New mammals from the Rexroad fauna, upper Bartow, J.A. 1996. Geologic map of the west border of the San Pliocene of Kansas. American Midland Naturalist 26:337–368. Joaquin Valley in the Panoche Creek-Cantua Creek area, Fresno Kelly, T.S., and J.D. Stewart. In press. New records of middle and and San Benito Counties, California. U.S. Geological Survey late Miocene Perissodactyla and Artiodactyla from the western Miscellaneous Investigations Series. border of the San Joaquin Valley, Diablo Range, Fresno County, Baskin, J.A. 1998. Mustelidae. Pp. 152–173 in C.M. Janis, K.M. California. Contributions in Science, Natural History Museum Scott, and L.L. Jacobs (eds.). Evolution of Tertiary Mammals of of Los Angeles County. North America, Volume 1: Terrestrial Carnivores, Ungulates, and Lee, S., and P.J. Mill. 2004. Cranial variation in British mustelids. Ungulatelike Mammals. Cambridge University Press, Cambridge. Journal of Morphology 260:57–64. Bjork, P.R. 1970. The Carnivora of the Hagerman local fauna (late Linnaeus, C. 1758. Systema naturae per regna tria naturae, se- Pliocene) of southwestern Idaho. Transactions of the American cundum classes, ordines, genera, species, cum characteribus, Philosophical Society, Philadelphia, New Series 60:1–54. differentiis, synonymis, locis. Vol. 1: Regnum animale. Editio TSENG ET AL.—NEW MUSTELID FROM THE MIDDLE MIOCENE TEMBLOR FM. OF CA 23

decima, 1758 (12th edition of Linaeus 1758), Volume 1. Soci- APPENDIX 1 etatis Zoologicae Germanicae, Stockholm. List of morphological characters and their states used in Long, C.A. 1974. Growth and development of the teeth and skull the cladistic analysis. of the wild Nort American badger, Taxidea taxus. Transactions of the Kansas Academy of Sciences 77:106–120. Character 1*: P1 (0) present (1) absent. Marshall, W.H. 1951. An age determination method for the pine Character 2*: p1 (0) present (1) absent. marten. Journal of Wildlife Management 15:276–283. Character 3*: P4 medial shelf (0) absent or restricted to area Merriam, J.C. 1914. Correlation between the Tertiary of the Great between paracone and protocone (1) expands anteriorly and Basin and that of the marginal marine province in California. posteriorly (2) shelf runs entire lingual side. Science 40:643–645. Character 4*: P4 protocone (0) conical cusp (1) shelf only. Merriam, J.C. 1915. Tertiary vertebrate faunas of the North Character 5*: P4 hypocone (0) absent (1) present. Coalinga region of California. Transactions of the American Character 6*: p4 posterior accessory cusp (0) present (1) Philosophical Society 22:191–234. absent. Peigné, S., L.d. Bonis, A. Likius, H.T. Mackaye, P. Vignaud, and Character 7*: M1 (0) metacone small relative to paracone M. Brunet. 2008. Late Miocene Carnivora from Chad: Lutrinae (1) metacone as large as paracone (2) metacone lost. (Mustelidae). Zoological Journal of Linnean Society 152:793–846. Character 8: Inter-dental gaps between premolars (0) absent Pilgrim, G.E. 1932. The genera Trochictis, Enhydrictis, and Tro- (1) present. charion, with remarks on the taxonomy of the Mustelidae. Character 9: P4 protocone (0) aligned with parastyle (1) Proceedings of the Zoological Society of London 4:845–867. offset posteriorly from parastyle. Qiu, Z.-x., T. Deng, and B.-y. Wang. 2004. Early Pleistocene Character 10: m1 trigonid length (0) longer than or equal mammalian fauna from Longdan, Dongxiang, Gansu, China. to talonid (1) shorter than talonid. Palaeontologia Sinica Series C 191:1–198, with 39 plates. Character 11: M1 metaconule (0) absent (1) present. Ray, C.E., E. Anderson, and S.D. Webb. 1981. The Blancan carni- Character 12: M1 posterior border (0) slightly bulging in- vore Trigonictis (Mammalia: Mustelidae) in the eastern United ternally (1) formation of internal “ear”. States. Brimleyana 5:1–36. Character 13: Infraorbital foramen (0) small (1) enlarged. Simpson, G.G. 1945. The principles of classification and a classifica- Character 14: P4 paracone anterior ridge (0) present (1) tion of mammals. Bulletin of the American Museum of Natural absent. History 8:1–350. Character 15: m1 metaconid size (0) small relative to pro- Stefen, C. 1994. Zahnschmelzdifferenzierungen bei Raubtieren: toconid (1) close to equal in size and level as protoconid. [Carnivora im Vergleich zu Vertretern der Creodonta, Arctocy- Character 16: P4 cusp (0) not inflated (1) inflated and onidae, Mesonychidae, Entelodontidae (Placentalia), Thylaco- bulbous. leonidae, Dasyuridae und Thylaacinidae (Marsupialia)]. Ph.D. diss., Rheinischen Friedrich-Wilhelms-Universtat zu Bonn. Character 17*: Anterior opening of palatine canals (0) adja- Stefen, C. 1997. Chapter 7. Differentiations in Hunter-Schreger bands cent to P4 (1) adjacent to P3. of carnivores. Pp. 123–136 in W.v. Koenigswald and P. M. Sander Character 18*: Orientation of infraorbital foramen opening (eds.). Tooth enamel microstructure. A.A. Balkema, Rotterdam. directed (0) anteriorly (1) antero-ventrally. Stefen, C. 2001. Enamel structure of arctoid Carnivora: Amphi- Character 19*: Paroccipital process (0) present (1) absent. cyonidae, Ursidae, Procyonidae, and Mustelidae. Journal of Character 20: Pre-glenoid process (0) smaller than post- Mammalogy 82:450–462. glenoid process (1) same size. Swofford, D.L. 1993. Phylogenetic analysis using parsimony Character 21: Zygomatic arch depth (0) less than or equal (PAUP), version 3.1.1. Illinois Natural History Survey, Urbana. two twice the zygomatic width (1) more than twice the Tedford, R.H., T. Galusha, M.F. Skinner, B.E. Taylor, R.W. Fields, zygomatic width. J.R. Macdonald, J.M. Rensberger, S.D. Webb, and D.P. Whistler. Character 22: Sagittal crest (0) ends at occipital (1) hangs 1987. Faunal succession and biochronology of the Arikareean over the occipital. through Hemphillian interval (Late Oligocene through earliest *Characters modified from Bryant et al. (1993). Miocene epochs) in North America. Pp. 153–210 in M.O. Wood- burne (ed.). Cenozoic Mammals of North America, Geochronol- APPENDIX 2 ogy and Biostratigraphy. University of California Press, Berkeley. List of extant specimens used in the cladistic analysis: Tedford, R.H., L.B. Albright, III, A.D. Barnosky, I. Ferrusquía- Villafranca, R.M. Hunt, Jr., J.E. Storer, C.C. Swisher, III, M.R. Eira barbara LACM[M]10078, 13751; Galictis vittata Voorhies, S.D. Webb, and D.P. Whistler. 2004. Mammalian LACM[M]70236; Gulo gulo LACM[M]31569; Lontra biochronology of the Arikareean through Hemphillian interval canadensis ZJT comparative collection J050607T01; (Late Oligocene through Early Pliocene Epochs). Pp. 169–231 Martes americana L ACM[M]10668, 27377, 33377, in M.O. Woodburne (ed.). Late Cretaceous and Cenozoic Mam- 92393; Martes martes LACM[M]74508; Martes pennanti mals of North America. Columbia University Press, New York. LACM[M]54254.